The condition of former South African president Nelson Mandela, who is being treated for a reoccurring lung infection in hospital, has become critically ill, the South African presidency has reported.

South African President Jacob Zuma visited the Nobel Peace Prize winner in the Medi-Clinic Hospital in Pretoria today where he was brief by Mr Mandela’s medical team, according to Mac Maharaj, his spokesperson.

The medical team informed them that Mr Mandela’s condition had become critical over the past 24 hours.

“The doctors are doing everything possible to get his condition to improve and are ensuring that Madiba [Mr Mandela’s clan name] is well-looked after and is comfortable. He is in good hands,” said Mr Zuma said in the statement.

Mr Mandela has been in hospital for over two weeks receiving treatment for a reoccurring lung infection.

Until Sunday, official communiques had described his condition as “serious but stable” although comments last week from Mandela family members and his presidential successor, Thabo Mbeki, suggested he was on the mend.

Since stepping down after one term as president, Mr Mandela has played little role in the public or political life of the continent’s biggest and most important economy.

His last public appearance was waving to fans from the back of a golf cart before the final of the soccer World Cup in Johannesburg’s Soccer City stadium in July 2010.

During his retirement, he has divided his time between his home in the wealthy Johannesburg suburb of Houghton, and Qunu, the village in the impoverished Eastern Cape province where he was born.

The public’s last glimpse of him was a brief clip aired by state television in April during a visit to his home by Mr Zuma and other senior ANC officials.

At the time, the 101-year-old liberation movement, which led the fight against white-minority rule, assured the public Mr Mandela was “in good shape” although the footage showed a thin and frail old man sitting expressionless in an armchair.

“Obviously we are very worried,” ANC spokesman Jackson Mthembu told Johannesburg station Talk Radio 702. “We are praying for him, his family and the doctors.”

Since his latest admission to hospital, well-wishers have been arriving at his Johannesburg home, with scores of school-children leaving painted stones outside the gates bearing prayers for his recovery.

However, for the first time, South African media have broken a taboo against contemplating the inevitable passing of the father of the post-apartheid ‘Rainbow Nation’ and one of the 20th century’s most influential figures.

The day after he went into hospital, South Africa’s Sunday Times newspaper carried a front-page headline saying it was “time to let him go”.

“He’s absolutely an icon and if he’s gone we just have to accept that. He will be gone but his teachings, what he stood for, I’m sure we’ve all learnt and we should be able to live with it and reproduce it wherever we go,” said Tshepho Langa, a customer at a Johannesburg hotel. “He’s done his best,” he added.

“We are grateful for it and we are willing to do the good that he has done.”

Despite the widespread adulation, Mr Mandela is not without detractors at home and in the rest of Africa who feel that in the dying days of apartheid he made too many concessions to whites, who make up just 10 per cent of the population.

After more than 10 years of affirmative action policies aimed at redressing the balance, South Africa remains one of the world’s most unequal societies, with whites still controlling much of the economy and the average white household earning six times more than a black one.

“Mandela has gone a bit too far in doing good to the non-black communities, really in some cases at the expense of (blacks),” Zimbabwean president Robert Mugabe (89) said in a documentary aired on South African television this month.